Modern disc drives are commonly used in a multitude of computer environments, ranging from super computers to notebook computers, to store large amounts of data in a form that is readily available to a user. Typically, a disc drive has one or more magnetic discs that are rotated by a spindle motor at a constant high speed. Each disc has a data storage surface divided into a series of generally concentric data tracks that are radially spaced across a band having an inner diameter and an outer diameter. The data is stored within the data tracks on the disc surfaces in the form of magnetic flux transitions. The flux transitions are induced by an array of read/write heads. Typically, each data track is divided into a number of data sectors where data is stored in fixed size data blocks.
The read/write head includes an interactive element such as a magnetic transducer. The interactive element senses the magnetic transitions on a selected data track to read the data stored on the track. Alternatively, the interactive element transmits an electrical signal that induces magnetic transitions on the selected data track to write data to the track.
Each of the read/write heads is mounted to a rotary actuator arm and is selectively positioned by the actuator arm over a pre-selected data track of the disc to either read data from or write data to the data track. The read/write head includes a slider assembly having an air bearing surface that, in response to air currents caused by rotation of the disc, causes the head to fly adjacent to the disc surface with a desired gap separating the read/write head and the corresponding disc.
Typically, multiple center-open discs and spacer rings are alternately stacked on a spindle motor hub. The hub, defining the core of the stack, serves to align the discs and spacer rings around a common axis. Collectively the discs, spacer rings and spindle motor hub define a disc pack assembly. The surfaces of the stacked discs are accessed by the read/write heads which are mounted on a complementary stack of actuator arms which form a part of an actuator assembly. The actuator assembly generally includes features which conduct electrical signals from the read/write heads to a flex circuit which, in turn, conducts the electrical signals to a flex circuit connector mounted to a disc drive base deck.
When the disc drive is not in use, the read/write heads are parked in a position separate from the data storage surfaces of the discs. Typically, a landing zone is provided on each of the disc surfaces where the read/write heads are positioned before the rotational velocity of the spinning discs decreases below a threshold velocity which sustains the air bearing. The landing zones are typically located near the inner diameter of the discs.
Generally, the actuator assembly has an actuator body that pivots about a pivot mechanism that is receivingly disposed in a medial portion thereof. A motor, such as a voice coil motor, selectively positions a proximal end of the actuator body. This positioning of the proximal end in cooperation with the pivot mechanism causes a distal end of the actuator body, which supports the read/write heads, to move radially across the face of the discs.
The voice coil typically involves energizing an electrical coil that is supported by the pivotal actuator assembly in a manner that positions the electrical coil adjacent a stationary magnet assembly. A controlled current in the electrical coil thus causes the electrical field of the electrical coil to interact with the magnetic field of the magnet assembly to move the actuator assembly in accordance with the well-known Lorentz relationship.
The movement of the actuator assembly creates reactionary forces in the stationary magnet assembly that excite resonances in the disc drive assembly. A well known problem involves read/write head positioning errors caused by servo noise resulting from this resonance.
One approach to resolving this problem is associated with attempts to dampen the magnet assembly with respect to the disc drive enclosure. These attempts have met with difficulty and a lack of success. Due to manufacturing tolerance stacking, the traditional approach of using a compressed gasket has been shown likely to result in either an over-compression or an under-compression of the compressed gasket. The former can prevent proper sealing of the disc drive enclosure, and the latter can effectively nullify the damping affect.
There currently is a need in the art for a damper that will effectively and reliably dampen the resonance imparted to the disc drive by the magnet assembly and accommodate variations in the assembly of the magnet assembly within the disc drive.